1. Field of the Invention
The present invention relates generally to improvements in an electronic musical instrument which is capable of imparting the natural slur effect to musial tones by smoothly changing pitch of the musical tones from that of a musical tone generated by a firstly-depressed key (the first key) to that by a secondly-depressed key (the second key).
More specifically, the invention concerns an electronic musical instrument which can eliminate such uncomfortability or unnaturality listeners feel that the musical tones imparted with the slur effect or (portamento effect) are increased or decreased in audio volume level between musical tones even if the two or more tones actually have an equal volume level, by changing the amplitude coefficient of the musical tones according to their pitches so as to control the volume level of the musical tones.
2. Description of the Prior Art
There has been so far suggested, for example, in Japanese Patent Application Laid-open No. 107722/1979 an electronic musical instrument wherein the slur effect can be imparted to musical tones by smoothly changing the pitch of the musical tones from that of a musical tone generated by the first-operated key (the first key) to that by the next-operated key (the second key).
If a player performs the slur playing operation on a natural instrument such as a guitar, the volume level of the played musical tones will be naturally varied according to the pitch of the tones, imparting the natural slur effect to the musical tones. In a slur operation, a listener generally senses that a higher-frequency tone is louder than a lower-frequency tone, even if the tones actually have an equal volume level.
Such conventional electronic musical instrument has a disadvantage in that the musical tones are varied only in pitch (frequency) and thus it is impossible to obtain a slur effect similar to that of a natural instrument, and listeners feel the slur effect uncomfortable or unnatural because they feel the volume of the tone have different levels even if these tones actually have an equal volume level.